Background: Primary retroperitoneal dermoid cysts, also referred to as mature cystic teratomas, are rare benign germ cell tumors composed of well-differentiated derivatives of one or more embryonic germ layers. Although teratomas are commonly encountered in gonadal locations, extra-gonadal retroperitoneal occurrence is distinctly uncommon, and adrenal or suprarenal involvement is particularly rare in adults. Because these lesions frequently contain macroscopic fat, sebaceous material, hair, calcification, and soft tissue components in varying proportions, their radiological appearance may overlap with other fat-containing retroperitoneal tumors such as adrenal myelolipoma, angiomyolipoma, lipoma, or even liposarcoma. In the absence of obvious calcified teeth, bone, or characteristic Rokitansky protuberance, accurate preoperative diagnosis may be difficult. Such diagnostic ambiguity may lead to an initial radiological impression favouring a more common suprarenal lesion i.e. Angiomyolipoma.

Case Presentation: We report the case of a 35-year-old female who presented with intermittent right upper abdominal pain for 4 months. Clinical examination was largely unremarkable, and no palpable abdominal mass was identified. Contrast enhanced computed tomography of the abdomen and pelvis revealed a well-defined, non-enhancing, predominantly hypodense lesion of fat attenuation with interspersed soft tissue components measuring approximately 6.8 x 7.4 x 9.3 cm in the right suprarenal region. The lesion produced mass effect on the adjacent liver and upper pole of the right kidney, and the right adrenal gland could not be visualized separately. Based on these findings, a preoperative radiological diagnosis of right adrenal angiomyolipoma was made. In view of the patient’s symptoms and the size of the lesion, exploratory laparotomy with excision was undertaken. Intraoperatively, a well-encapsulated cystic mass was identified in the right suprarenal retroperitoneum. On opening the lesion, abundant matted hair and thick sebaceous material were encountered, which was highly suggestive of a dermoid cyst. Complete excision of the cyst wall and contents was achieved without spillage. Histopathological examination confirmed the diagnosis of a mature cystic teratoma (dermoid cyst). The postoperative course was uneventful, and the patient was discharged in stable condition on postoperative day 4.

Discussion: This case highlights an important diagnostic pitfall in the evaluation of fat-containing adrenal-region masses. Although computed tomography is highly sensitive for detecting fat, it may not always reliably distinguish sebaceous material within a dermoid cyst from adipose tissue within lesions such as angiomyolipoma or myelolipoma. Mature cystic teratoma should therefore remain an important differential diagnosis for well-circumscribed suprarenal masses showing dominant fat attenuation, especially when imaging findings are atypical or when the adrenal gland cannot be clearly separated from the lesion. Definitive diagnosis depends on surgical excision and histopathological evaluation.

Conclusion: Primary retroperitoneal dermoid cyst arising in or near the adrenal region is a rare but important differential diagnosis of fat-containing suprarenal masses. This case demonstrates that a dermoid cyst may closely mimic right adrenal angiomyolipoma on preoperative imaging. Complete surgical excision remains both diagnostic and curative, with an excellent postoperative outcome in benign lesions.

KEYWORDS: Dermoid Cyst, Mature Cystic Teratoma, Adrenal Mass, Suprarenal Lesion, Angiomyolipoma, Retroperitoneal Tumor.